Abstract: Objective To evaluate the occupational health risks of phosphine exposure in inspection workers of two sewage treatment plants in Beijing,and provide suggestions for further reducing the risk of phosphine exposure. Methods Operators involved in phosphine in two sewage treatment plants（A and B） in Beijing were selected as the study subjects. In April and June 2023,on-site sampling method was used to measure phosphine concentration in the normal production stage of the enterprises. Combined with exposure time,frequency,years and other factors,the environmental protection agency（EPA） inhalation non-cancer risk model and occupational hazard classification method were used to evaluate the occupational health risks of phosphine among workers in plants A and B. Results The non-cancer hazard quotient（HQ） of phosphine exposure for sewage treatment operator, sludge thickening dewatering operator and sludge nitrification operator in plant A were 40.65,15.84 and 3.45,respectively. B plant wastewater treatment operator phosphine non-cancer HQ was 8.9. The non-cancer risk indicators of phosphine in inspection operations of both plants A and B were greater than 1. Plants A and B were relatively harmless operations（level 0）. Conclusion The occupational health risks associated with phosphine are high in urban sewage treatment plants,and further comprehensive measures of engineering technology and occupational health management practices should be taken to reduce occupational exposure health risks of phosphine.

Key words: Sewage treatment plant, Phosphine, Health risk assessment, Occupational health